Abstract The soft and hard regimes of generation of periodic fluctuations in the supersonic boundary layer at moderate (M = 2) and high (M = 5.35) Mach numbers are investigated within the framework of weakly nonlinear theory. The model includes both the effects of self-action which are inherent in incompressible fluid flows (generation of secondary steady-state harmonics and generation of double-frequency perturbations) and the cubic terms of original fluctuations appearing only for compressible gas. The study of the nature of generation of periodic regimes in the neighborhood of the neutral curve in compressible flows is useful since it can lead to new results that are necessary for understanding the laminar-turbulent transition laws.

中文翻译：

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从超音速边界层中性曲线分支出来的自振荡

摘要 在弱非线性理论的框架内研究了在中等 (M = 2) 和高 (M = 5.35) 马赫数下超音速边界层中产生周期性波动的软硬机制。该模型包括不可压缩流体流动固有的自作用效应（二次稳态谐波的产生和双频扰动的产生）和仅对可压缩气体出现的原始波动的三次项。研究可压缩流中中性曲线附近周期性状态的产生性质是有用的，因为它可以导致理解层流-湍流转变规律所必需的新结果。